Streamline trace implementation

Avoid creation of `op1` methods if tracing is not enabled.

Author: odersky

compiler/src/dotty/tools/dotc/reporting/trace.scala

@@ -14,25 +14,30 @@ object trace {
     conditionally(ctx.settings.YdebugTrace.value, question, false)(op)
 
   @inline
-  def conditionally[TC](cond: Boolean, question: => String, show: Boolean)(op: => TC)(implicit ctx: Context): TC = {
-    def op1 = op
-    if (Config.tracingEnabled && cond) apply[TC](question, Printers.default, show)(op1)
-    else op1
-  }
+  def conditionally[TC](cond: Boolean, question: => String, show: Boolean)(op: => TC)(implicit ctx: Context): TC =
+    if (Config.tracingEnabled) {
+      def op1 = op
+      if (cond) apply[TC](question, Printers.default, show)(op1)
+      else op1
+    } else op
 
   @inline
-  def apply[T](question: => String, printer: Printers.Printer, showOp: Any => String)(op: => T)(implicit ctx: Context): T = {
-    def op1 = op
-    if (!Config.tracingEnabled || printer.eq(config.Printers.noPrinter)) op1
-    else doTrace[T](question, printer, showOp)(op1)
-  }
+  def apply[T](question: => String, printer: Printers.Printer, showOp: Any => String)(op: => T)(implicit ctx: Context): T =
+    if (Config.tracingEnabled) {
+      def op1 = op
+      if (printer.eq(config.Printers.noPrinter)) op1
+      else doTrace[T](question, printer, showOp)(op1)
+    }
+    else op
 
   @inline
-  def apply[T](question: => String, printer: Printers.Printer, show: Boolean)(op: => T)(implicit ctx: Context): T = {
-    def op1 = op
-    if (!Config.tracingEnabled || printer.eq(config.Printers.noPrinter)) op1
-    else doTrace[T](question, printer, if (show) showShowable(_) else alwaysToString)(op1)
-  }
+  def apply[T](question: => String, printer: Printers.Printer, show: Boolean)(op: => T)(implicit ctx: Context): T =
+    if (Config.tracingEnabled) {
+      def op1 = op
+      if (printer.eq(config.Printers.noPrinter)) op1
+      else doTrace[T](question, printer, if (show) showShowable(_) else alwaysToString)(op1)
+    }
+    else op
 
   @inline
   def apply[T](question: => String, printer: Printers.Printer)(op: => T)(implicit ctx: Context): T =